interpretor/preprocessor/faust-0.9.47mr3/tools/faust2pd/examples/faust/lfboost.dsp

   1 declare name            "lfboost";
   2 declare version         "1.0";
   3 declare author          "Grame";
   4 declare license         "BSD";
   5 declare copyright       "(c)GRAME 2006";
   6
   7 //------------------------------------------------------------------
   8 //      DAFX, Digital Audio Effects (Wiley ed.)
   9 //      chapter 2       : filters
  10 //      section 2.3 : Equalizers
  11 //      page 53         : second order shelving filter design
  12 //------------------------------------------------------------------
  13
  14 import("math.lib");
  15 import("music.lib");
  16
  17
  18 //----------------------low frequency boost filter -------------------------------
  19 // lfboost(F,G)
  20 //                              F :     frequency (in Hz)
  21 //                              G : gain (in dB)
  22 //
  23 //--------------------------------------------------------------------------------
  24
  25 lfboost(F,G)    = TF2(  (1 + sqrt(2*V)*K + V*K*K) / denom,
  26                                                  2 * (V*K*K - 1) / denom,
  27                                                 (1 - sqrt(2*V)*K + V*K*K) / denom,
  28                                                  2 * (K*K - 1) / denom,
  29                                                 (1 - sqrt(2)*K + K*K) / denom
  30                                          )
  31                 with {
  32                         V                       = db2linear(G);
  33                         K                       = tan(PI*F/SR);
  34                         denom           = 1 + sqrt(2)*K + K*K;
  35                 };
  36
  37
  38
  39 //====================low frequency boost process ===============================
  40
  41 process = vgroup("lowboost", lfboost(
  42                                                                 nentry("freq (Hz)", 100, 20, 150, 1),
  43                                                                 vslider("gain (dB)", 0, -20, 20, 0.1)
  44                                 ) );